OBJECTIVES: 1) The biochemical characterization of selected respiration-deficient Chinese hamster cell mutants will be continued. 2) We hope to complete the mapping of the gene of a component of succinate dehydrogenase on human chromosome #1. 3) Oligomycin resistance in hamster cells is being studied to determine if it is determined by a nuclear or cytoplasmic gene. 4) Several temperature-sensitive hamster mutants with a defect in G1 of the cell cycle are being studied, with particular emphasis on the inducibility at the nonpermissive temperature of the enzymes ornithine decarboxylase, SAM decarboxylase, thymidine kinase, and ribonucleotide reductase. 5) Variants resistant to the analogue alpha-methylornithine are being selected and studied.